This invention relates to a package assembly which includes a group of usually rectangular, individual, gas-pervious packages and an outer wrapper enveloping the group. The content of the individual packages is gas-releasing, such as freshly roasted coffee.
Conventionally, roasted coffee beans are packaged in gastight simple bags for preserving their flavor. Because of the natural gas emission of freshly roasted coffee, the bags inflate and appear to the customers as incompletely filled packages. If, on the other hand, the bags are not gastight to thus permit the gas, particularly carbon dioxide, to escape, at the same time the aromatic substances also escape. Further, a gas exchange may take place, as a result of which oxygen may enter into the bags which, as known, leads to an accelerated decomposition of certain aromatic substances. For this reason the bags have to be sold within a certain period of time within which at the most only a small amount of inflation of the bag may be noticed or before the released gas entrains with it aromatic substances to an appreciable extent.
In packaging foodstuff in vacuumtight foil bags it is known, as disclosed, for example, in U.S. Pat. No. 2,638,263, to incorporate in the wrapper a check valve through which air is evacuated from the bag, but which subsequently prevents air from entering the bag from the environment.
It is further known, as disclosed in Swiss Pat. No. 561,132, to wrap articles in gastight shrinking foils and to evacuate the package prior to sealing it gastight.
Packaging of roasted coffee according to the two above-outlined exemplary possibilities has several disadvantages. To provide each individual bag with its own relief valve is very expensive. Such a packaging needs new packing machines which, in a high-output operation, have to provide for the supply and sealing of the individual relief valves to the single bags. In present-day bagging machines which operate with high-frequency cycles, such an additional operation could, in any event, be performed only with difficulty, if at all. On the other hand, a shrinking foil package may be used only in connection with foodstuff which does not release any gases, otherwise the above-noted disadvantageous bloating of the package will occur.